This invention relates to the manufacture of composite products, such products to be defined as containing chemically dissimilar materials most generally typified by an organic nonpolar substance and an inorganic polar substance. Specifically, the invention describes the preparation and use of novel mixed metal metallo-organic substances which are useful in chemically modifying the particulate or fibrous materials which most often are inorganic for incorporating into the resin matrices with which they will share an interfacial boundary.
It is recognized by those skilled in the art that manufacture of mineral filled or fiber reinforced plastic or rubber articles offers unique problems associated with the poor wetting of the mineral or fiber by the resin. Subsequently, interfacial failure can occur and is augmented in most applications by the presence of moisture which migrates to the interface in the absence of any surface treatment of the mineral filler or fiber and will result in substantial loss in flexural and tensile strength properties. An identical problem is observed in analogous composite systems such as paints and coatings, paper, adhesives, sealants and other compositions containing the organic/inorganic interface.
Historically, fibers, most specifically fiber glass, have been treated with methacrylato chromic chlorides as disclosed in: U.S. Pat. Nos. 2,273,040; 2,524,803; 2,552,910; 2,544,666; 2,544,667; 2,544,668; 2,611,718; and trialkoxy silanes as disclosed in: U.S. Pat. Nos: 2,742,378, 2,776,910, 2,832,754, 2,930,809, 2,946,701, 3,045,036, 3,169,884, 3,211,684, 3,258,477, 3,849,471.
Both of these materials impart additional dry and wet strength properties to glass reinforced fabricated articles. Silanes have also enjoyed usage as a preferred surface treatment for mineral fillers such as silica, alumina trihydrate, mica, wollastonite, and glass beads, when such are to be used in applications wherein physical strength of the composite is an important performance property. More recently, organo titanates, such as described in U.S. Pat. Nos. 4,096,110; 4,098,758; 4,141,751; and 4,152,311 have found some application in mineral filled thermoplastic composites. In other less demanding applications as are found in paper manufacture and some coatings areas it is viable to use surfactants or fatty acid salts to chemically alter the inorganic substrate.
The usefulness of silanes is partially offset by their high cost, a requirement of heat input to react the silanes with fillers, and handling problems related to rapid hydrolysis and polymerization in the presence of moisture, which greatly reduces their effectiveness. Titanates are also hindered by undesireable economics, albeit not as severe as silanes, and also by their limited application in aqueous environments and in products wherein strength properties are significant.
The compositions described herein are unique substances which are highly soluble in water and a variety of polar organics, hydrolytically stable, cost effective viz-a-viz the aforementioned silanes and titanates, and highly reactive, reacting essentially instantaneously with mineral fillers and functional organic particulates at ambient temperature. The said compositions are predicated upon an important symbiotic relationship, which combines the preferred activity of inorganic substrates for the aluminum portion of the molecule and the advantages of using a tetravalent transition metal for purposes of complexation with a reactive organic.